Recreational sport boats are often used to tow water sports performers such as water skiers, wakeboarders, wake surfers, and the like. The optimal wake depends on which of these water sports a boat is used for, as well as the preferences and skill level of the performer. Water skiers generally prefer a relatively smooth water surface, while wake-boarders and wake surfers desire bigger wakes and wakes with more defined shapes. In recent years, boats have been equipped with various means for modifying the wake of the boat depending on how the boat is being used.
One example of a conventional means used to modify a boat's wake is a trim tab. Trim tabs originally were designed to adjust the trim of a boat. For example, when a boat is overloaded on the port side causing the boat to list to port, a turn tab may be deployed on the port side to cause the boat to return to an even keel. More recently, trim tabs have been used to purposefully modify the wake of a boat. One way to do so is to use one or more trim tabs to lift the stem of the boat. Lifting the stern minimizes the wake of a boat, resulting in a relatively smooth water surface, which is desirable for water skiing. Another way that trim tabs have been used is to increase the displacement of one side of the boat, which increases the size of the wake on the side of the boat with the increased displacement.
FIG. 1 shows the transom 122 of a boat used to tow a water sports performer. Three trim tabs 10, 20, 30 known in the art are mounted on the transom 122: one on the port side, one at the centerline, and one on the starboard side. Each tab is pivotably attached to the transom 122 of the boat by a hinge 11, 21, 31. The port and starboard trim tabs 10, 30 axe flat plates, with inboard and outboard edges bent upwards at a 90° angle. The upwardly-extending portion of each tab extends approximately ¼ inch above the upper surface of the flat portion of the tabs. The center trim tab 20 also is a flat plate, with inboard and outboard edges bent downwards at a 90° angle and a trailing edge bent upwards at a 90° angle. The downwardly-extending portions of the center tab extend approximately ⅛ inch below she lower surface of the fiat portion of the tab, and the upwardly-extending portion extends approximately ¼ inch above the upper surface of the flat portion. The edges of the trim tabs 10, 20, 30 are bent upwards or downwards to aid in the manufacturing process and the extent to which the edges extend upwards or downwards is preferably minimized.
Each of the aforementioned trim labs 10, 20, 30 is pivotable between a non-deployed position and a deployed position. In FIG. 1, the port trim tab 10 is shown in a deployed position and the starboard trim tab 30 is shown in a non-deployed position. A linear actuator 510 moves each tab between the non-deployed position and the deployed position. As the boat moves through the water, the water flowing under the boat impinges on the deployed trim tab, creating an upward force on the tab. As a result, the portion of the bout where the trim tab is attached is raised. When used for water skiing, the center tab 20 may be deployed to raise the entire stern of the boat and minimize the wake. To increase the wake of the boat for wake surfing, either one of the port or starboard trim tabs may be deployed. When the port trim tab 10 is deployed, for example, the port side of the boat is raised, causing an increase in displacement on the starboard side of the boat, which increases the size of the starboard wake. The side of the boat with the increased wake is the surf side, which, in this example, is the starboard side. To further increase the size of the wake, ballast may also be added to the surf side of the boat.
In the embodiment shown in FIGS. 1 and 2, the port and starboard trim tabs 10, 30 are not perfectly rectangular, but rather have an angled contour along their outboard edges. This is so that the trim tabs do not extend beyond the outer perimeter of a swim platform (not shown) mounted to the transom 122 of the boat, above the trim tabs 10, 20, 30. Alternatively, all of the trim tabs may-have a rectangular shape.
Even with the trim tabs described above, wakeboarders and wake surfers desire larger wakes with improved shapes. For surfing in particular, wake surfers desire a wake with a large surfable area. The surfable area is the portion of the wake that pushes the surfer forward. This area generally extends from the curl of the wake to the swim platform.